It didn't belong to a dead aunt of Anna Ayala, who made the claim. Nor was the owner a woman who got too friendly with her pet leopard.
The finger came from a man who lost it in an industrial accident and gave it to the husband of Ayala, who allegedly planted it in a scam to get money.
"The puzzle pieces are beginning to fall into place, and the truth is being exposed," police Chief Rob Davis said at a news conference Friday.
Davis said a tip was called in to a hot line established by the Ohio-based fast-food chain, and police found the man in Nevada this week. He said scientific tests confirmed the finger was his.
Investigators had initially believed the 1½-inch fragment was a woman's because the nail was well-trimmed.
Davis would not identify the man or say why they think he gave the finger to Ayala's husband. The nature of the industrial accident was also not disclosed. They said only that the man was an associate of Ayala's husband, a construction worker.
Authorities said last month that they believed the story was a hoax, and they arrested Ayala at her home in Las Vegas and charged her with attempted grand larceny for allegedly trying to shake down Wendy's.
Ayala, 39, filed a claim against the restaurant chain shortly afterward, but later withdrew it as she came under scrutiny. Investigators found at least 13 cases in which she has filed claims in her name or her children's.
During the investigation, Wendy's said no employees at the San Jose restaurant had missing fingers, and no suppliers of Wendy's ingredients had reported any finger injuries. Authorities reported that there was no evidence the finger had been cooked.
Calls to an attorney for Ayala and Jaime Plascencia, her husband, were not immediately returned. Plascencia is in jail on identity-theft charges unrelated to the Wendy's case.
Authorities are considering additional charges against the couple, Davis said.
"We are exploring all other options and avenues available to see that those involved in this charade will be investigated," the police chief said.
Wendy's has said it has lost millions in sales since Ayala made the claim while visiting her family in San Jose. Dozens of employees at the company's Northern California franchises also have been laid off.
The franchise where the claim was made saw an immediate 60 percent to 70 percent drop in business, said Stephen Jay, marketing director at JEM Management, which owns the restaurant. Business is still off 20 percent, he said.
The restaurant chain has offered a $100,000 reward but has not given it out yet, according to company spokesman Bob Bertini. He said officials need to talk with police to determine who should receive it.
In a statement, the company praised San Jose police and said the latest evidence vindicates its employees.
"We strongly defended our brand and paid a severe price," said Tom Mueller, Wendy's president of North America. "We are extremely proud of our employees and franchisees who have suffered the most, and we are forever grateful to our many customers who have supported us during this difficult time."
The Nevada agency that investigates industrial accidents has no record of a worker injury such as the one San Jose police described, said Tom Czehowski, chief administrator of the state Occupational Safety and Health Administration. Nevada employers are only required to report deaths or injuries causing the hospitalization of three or more employees, he said.
The California Division of Occupational Safety and Health was also checking its records for any workers who reported losing a finger in an industrial accident, spokesman Dean Fryer said.